Cornish party Mebyon Kernow sees the future in black and white

Dick Cole, right, leader of Mebyon Kernow (the Party for Cornwall), pictured at County Hall in Truro, with a fellow councillor, Loveday Jenkin. Photograph: Jim Wileman

When Loveday Jenkin was growing up, the Cornish flag was rarely seen. Now the white cross on a black background is ubiquitous, fluttering outside county hall in Truro and printed on everything from souvenir boxes of fudge to pasty packaging and car bumper stickers.

"I think it shows what a long way we've come in just a few years," says Jenkin, the latest member of Mebyon Kernow (MK) – the Party for Cornwall – to be elected to Cornwall council. "Everyone is so much more aware that we are separate, different, not a part of England and should have the right to govern ourselves."

Scotland has its own parliament, while the assemblies in Wales and Northern Ireland are maturing nicely. And in the far south-west MK is leading the campaign for a referendum on a Cornish assembly.

It is demanding a meeting with David Cameron and Nick Clegg to ask why a petition of 50,000 names, the equivalent of a tenth of the Cornish adult population, appears to have been ignored. The Welsh nationalist party, Plaid Cymru, has laid down an early-day motion in the Commons supporting the call for devolution.

MK, which has just celebrated its 60th birthday, is beginning to do well in local elections, holding five seats on Cornwall council – four more than Labour. The party hopes that the unpopularity of the Conservative-Liberal Democrat coalition will lead to it taking a leap forward at the next general election, and believes it is starting to attract younger voters disillusioned with the bigger parties.

"Being Cornish is about belonging to the place of Cornwall but also having a particular way of thinking about things," says Jenkin, a biochemist.

"We do things differently. Our culture is different, we have our own language. People ask why I identify myself as Cornish. It's simply because I am Cornish. We have more in common with Brittany and Wales than the south-east of England but we're subsumed into English decision-making."

But MK wants to go much further. It does not want full independence but a legislative assembly responsible for health, education, training, local government, housing, economic development, transport, energy, law and home affairs, environment, agriculture, forestry and fishing, sports and the arts.

Like Plaid, MK often talks about social justice. Dick Cole, the party's leader who gave up his job as an archaeologist to become a full-time councillor, says that over the past 40 years Cornwall's economy has been fractured.

"Jobs have been lost, centralised out of here," he said. "Cornwall is now one of the worst places for wages and the living costs are getting ever higher. We are one of the most deprived areas and the over-centralised nature of the British state has done us no good."

MK's policies include more affordable housing, "fairer taxation" under which the richer pay more and the poorer less, and – like the Welsh government – pushing for what it sees as an equitable funding deal from Westminster.

The unpopularity of the coalition could be just what MK needs. Cole says that during last year's election campaign, voters told him they wanted to back MK but felt they had to vote Lib Dem to keep the Tories out, or vice versa.

"Then the next thing was we have a Conservative-led coalition. People think they have been sold a pup and are telling us they will vote for us next time." When the Guardian ran its Disunited Kingdom? series of articles about devolution, it asked readers to say how they defined themselves in terms of nationality. The Cornish results were dominated by people who preferred to call themselves "other" rather than English or British. They were not given the option of describing themselves as Cornish.

Both Cole and Jenkin say they are Cornish first but British second. "If you do the history, the Celts are the ancient Britons. Being Cornish and British is completely logical," says Cole.

Jenkin points out that there had never been an act of union between Cornwall and England as there was between England and Scotland and England and Wales. She thinks of the monarch as "the queen" rather than "her queen", though MK would be prepared to let her open an assembly building if they get one. Jenkin also believes Prince Charles, the Duke of Cornwall, could do more to help champion the cause of Cornish separatism.

Cole and Jenkin are veteran MK activists but believe a new generation is beginning to take an interest; people such as John Rowe, a 25-year-old MK parish councillor.

Like many young Cornish people, Rowe admits he did not understand his identity until he left his family farm to go to university in Bath. "It may sound trite but I did not realise what Cornwall was all about until I left it," he said.

Rowe noticed not only the cultural differences – the language, the art – but also the economic differences between a relatively wealthy city such as Bath and the former mining town where he grew up, Camborne.

So will he see a Cornish assembly in his political career or even lifetime?

"I feel the tide is turning in our direction," he says. But he concedes that the turn could be slow.

Mebyon Kernow

Founded in 1951 at the Oates temperance hotel in Redruth, Mebyon Kernow's seven original aims included to "study local conditions and attempt to remedy any that may be prejudicial to the best interest of Cornwall", to "foster the Cornish language and literature" and "by self-knowledge to further the acceptance of the idea of the Celtic character of Cornwall, one of the six Celtic nations".

From its beginnings MK had a strong focus on Cornish identity and culture but was also openly political and by September 1951 the party had officially committed itself to Cornwall's "right to self-government in domestic affairs in a federated United Kingdom".

MK took a leap forward in the mid-60s when plans emerged for large-scale "overspill" developments in Cornwall to accommodate incomers from Greater London. It began to put forward official election candidates and in April 1967 party member Colin Murley won a seat on Cornwall county council fighting on an anti-overspill platform.

In the 70s MK held rallies in support of the fishing industry, marched against spiralling unemployment and fought the dumping of nuclear waste. The party also promoted Cornish cultural events and its members helped the comeback of the Cornish flag, as well as reviving the language and fighting for bilingual signs.

But during the 80s, after a rift in the party amid accusations that Trotskyists had infiltrated, there was a retreat from electioneering. By 1990 the party seemed close to collapse.

Then came a fightback. In 2000 MK launched a campaign calling for a Cornish assembly and within 15 months had collected 50,000 signatures supporting the move, the equivalent of a 10th of the electorate. It has just represented the petition to Downing Street 10 years on, demanding to know why it has not been acted on.

Buoyed by its success after the turn of the century the party fought for more seats than ever, joining battle in general elections as well as local ones. It outpolled Labour in Cornwall in the 2009 European election and in the same year put forward 33 candidates in the first unitary Cornwall council election.

It now has five seats on the Tory-controlled council, four more than Labour, and more than 25 town or parish councillors. MK remains a minority but, it likes to think, one with a big and growing voice.